EP1700271A1 - Processeur infographique et procede de rendu d'images - Google Patents

Processeur infographique et procede de rendu d'images

Info

Publication number
EP1700271A1
EP1700271A1 EP04806602A EP04806602A EP1700271A1 EP 1700271 A1 EP1700271 A1 EP 1700271A1 EP 04806602 A EP04806602 A EP 04806602A EP 04806602 A EP04806602 A EP 04806602A EP 1700271 A1 EP1700271 A1 EP 1700271A1
Authority
EP
European Patent Office
Prior art keywords
pass
blur
color
footprint
screen space
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04806602A
Other languages
German (de)
English (en)
Inventor
Kornelis Meinds
Bart G. B. Barenbrug
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Entropic Communications LLC
Original Assignee
Koninklijke Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=34717248&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP1700271(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Koninklijke Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Priority to EP04806602A priority Critical patent/EP1700271A1/fr
Publication of EP1700271A1 publication Critical patent/EP1700271A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T15/00—3D [Three Dimensional] image rendering
    • G06T15/005—General purpose rendering architectures

Definitions

  • the invention relates to a computer graphics processor and a method of rendering images.
  • This 2D transformation or mapping can be decomposed into a sequence of two orthogonal ID transformations, namely in a horizontal and in a vertical scanline order.
  • multi-dimensional image transformations of resampling operations can be executed as a sequence of one dimensional transformation.
  • one problem, that may arise within such a sequence of ID transformations, is the occurrence of aliasing due to shear.
  • the shear problem is illustrated in Fig. 1 showing two lines of a texture map (left side of Fig. 1) and an intermediate image (right side of Fig. 1).
  • a horizontal filter pass is performed, which however can not prevent vertical aliasing.
  • the shear causes a very sharp transition between black pixels in one line, and white pixels in the next.
  • One solution to the shear problem is the so-called super-sampling technique proposed by George Wolberg and Terrance E.
  • the super-sampling technique is a compute intensive approach.
  • Another approach to overcome the aliasing problem is based on a box filtering technique as described by Alvy Ray Smith, in "Planar 2-pass texture mapping and warping", in Computer Graphics (Proceedings Siggraph 1987), volume 21(4), pages 263 - 272, 1987.
  • prefiltering is applied and constitutes a process of checking whether a pixel is inside e.g. a triangle (for the case of inverse mapping).
  • the prefilter may have a delta function, a box function or the like.
  • each texel in the input texture is either mapped to screen space or not depending whether its position lies within the triangle.
  • a prefilter is used to determine which texels should contribute to a subsequent resampling, i.e. also possibly those not totally inside the triangle, in order to reduce edge aliasing.
  • An amount of overlap is determined between the triangle and a footprint of the prefilter, wherein the footprint of a prefilter corresponds to the area of the prefilter in the u/v directions in texture space.
  • Fig. 2 shows an illustration of an output pixel footprint mapped to the input image.
  • the left side of Fig. 2 shows a texture map 76, i.e. texels, in texture space, while the right side of Fig.
  • FIG. 2 shows an intermediate image after horizontal transformation 77, i.e. pixels.
  • the texture comprises a vertical column of grey texels 74.
  • the square 72 depicts a box reconstructed footprint of a texel, ML the midline, 75 white texels and 73 a mapped box reconstructed prefilter footprint of a pixel.
  • a box prefilter footprint of a pixel on a scanline 78 is shown in screen space. Accordingly, the footprint 78 of a box prefilter of the pixel on a scanline, indicated by the midline ML, is mapped to the texture space 76 and constitutes the mapped box reconstruction prefilter footprint.
  • a horizontal span of output pixels are modeled as a row of neighboring squares representing footprints of a box prefilter.
  • the footprint 73 of these pixels mapped to the scanline of the input image constitutes an area limited above and below by parallel line segments and left and right by curves and in particular straight lines for some transformations as shown in Fig. 2.
  • the pixel color being box filtered is composed of the average of the texel colors whose footprints of the box reconstruction filter intersects the mapped footprint 73 of the pixel.
  • a weighting function is performed on the texels in accordance of the size of the footprint area of the reconstruction filter 72 intersecting with the pixel's mapped footprint 73, i.e.
  • the renderer comprises a texture space rasterizer TS for rasterizing a primitive in texture space, a color generating unit PS for determining the color of the output of the texture space rasterizer TS and for forwarding a color sample along with coordinates, a 2-pass screen space resampler SSRI, SSR2 for resampling the color sample determined by the color generating unit PS, and at least one one-dimensional blur filter unit 1PB, 2PB associated to at least one pass of said screen space resampler SSRI, SSR2 for performing a ID filtering before performing at least one pass. Therefore, only ID calculations need to be performed during the resampling operation.
  • said processor comprises a first and second one-dimensional blur filter unit.
  • Said screen space resampler comprises a first pass and a second pass screen space resampler.
  • Said first blur filter unit is arranged before said first pass screen space resampler and said second blur filter unit is arranged before a second pass screen space resampler. Accordingly, the blur may be applied to both passes.
  • said first and second blur filter units are one-dimensional blur filters having footprints with a size depending on a corresponding shear factor, so that more blur may be introduced when there is more shear. Thus aliasing due to shear is effectively prevented.
  • said first and second blur filter units are box low pass filter having a weighted footprint. With such a footprint the contribution of a 2D footprint may be approximated more efficiently.
  • the invention also relates to a method of rendering images based on a forward mapping rendering. A primitive is rasterized in texture space. The color of the output of the rasterizing step is determined and a color sample is forwarded along with coordinates.
  • a 2- pass screen space resampling of the color sample determined in the color generating step is performed. At least one one-dimensional blur filtering is performed before performing at least one pass resampling.
  • the invention furthermore relates to a computer program product comprising program code means stored on a computer readable medium for performing an above method when said program is run on a computer Further aspects of the invention are defined in the dependent claims.
  • the invention is based on the idea to avoid the computation of an area overlap of the texel's footprint with the mapped footprint of a pixel, i.e. a 2D computation. Instead only 1 D computations are used by applying a ID filter to the texel.
  • Fig. 1 shows an illustration of aliasing due to shear caused by texture mapping
  • Fig. 2 shows an illustration of an output pixel footprint mapped to an input image
  • Fig. 3 shows a forward mapping pipeline according to a first embodiment of the invention
  • Fig. 4 shows a detailed illustration of the right hand side of Fig. 2 with a I D filtering
  • Fig. 5 shows an illustration of an improved ID filtering to approximate a 2D filter footprint
  • Fig. 6 shows an illustration of a shrunk footprint of Fig. 5
  • Fig. 7 shows an illustration of a weighting of the footprint of Fig. 6
  • FIG. 3 shows a forward mapping pipeline according to a first embodiment of the invention.
  • This forward mapping pipeline comprises a texture space rasterizer TS, a texture memory TM, a texture space resampler TSR, a pixel shader PS, a first pass and a second pass blur unit 1PB, 2PB, a first pass and a second pass screen space resampler SSRI, SSR2, and a pixel fragment combiner PFC.
  • the rasterization is performed in texture space and the texture space rasteriser TS traverses a projection of a primitive onto a texture map by selecting texture coordinates as variables for the rasterization process.
  • the texture space rasterizer TS may transverse the texture map on a texture grid. Texels being confined with the primitive or polygon being rasterized are to be splat on pixels in screen space. Therefore, the pixel shader PS and the texture space resampler TSR (of which there may be one or more, for serial or parallel fetching of texture samples, if several textures are present) correspond to those in a traditional pipeline.
  • the pixel shader PS receives a set of (interpolated) attributes, including texture and screen coordinates, for one location.
  • the texture coordinates determine where to index the texture maps via the texture space resampler TSR.
  • the shader can also modify texture coordinates before sending them to the texture space resampler TSR to implement dependent texturing, as in the same way as in a traditional pipeline.
  • the shader PS passes the shaded color on to the screen space resampler SSR, along with the associated screen coordinates. These in general are not integer, but this is similar to how a pixel shader in a traditional pixel shader pipeline might receive sub-pixel screen positions when performing super-sampling.
  • the screen space resampler SSR splats the mapped texels to integer screen positions, so that an image of the primitive is provided on the screen.
  • the pixel fragments from the screen space resampler SSR may be combined in the pixel fragment combiner PFC.
  • the shaded color sample resulting from the pixel shading process is forwarded to the screen space resampler SSR along with its screen coordinates.
  • the screen space resampler SSR resamples these color samples, (located generally at non-integer pixel positions) to the integer pixel positions needed for display. The screen space resampling is now described in more detail.
  • the approach to reduce the aliasing due to shear in the screen space resampling is based on an approximation of the box filtering technique and is directed to avoiding the computation of the area overlap of the (box reconstructed) footprint of a texel with the mapped footprint of a pixel.
  • This process is approximated using only 1 D computations over the midline: a 1 D blur (low pass) filter is applied to the texels with the filter footprint size depending on the local shear factor (resulting in more blur with more shear).
  • the shear factor may be received from the texture space rasterizer TS.
  • the blur may be applied both in the first (e.g. horizontal) pass and in the second (e.g. vertical) pass.
  • FIG. 4 shows a detailed view of the right side of Figure 2 but with the footprint of the box reconstructed texels mapped in output space. If merely the texel's ID footprint on the midline ML (indicated with the double sided arrow) would be mapped to the output space, a discontinuous diagonal line would be obtained, only represented with the indicated dark grey separate square areas. If the transformation with shear is applied on the 2D reconstruction footprint of the texels of the vertical line, a continuous parallelogram 20 consisting of the mapped footprints of these texels is obtained that represents the mapped line. The shear due to the 1 a pass is indicated by the distance 23.
  • the rasteriser can determine the location in the screen of half a pixel spacing above (this location was computed when rasterizing the previous line) and half a pixel spacing below the midline.
  • the horizontal distance 23 of the two screen locations corresponds to the horizontal shear factor.
  • the vertical shear factor can be determined by looking at the vertical distance of the screen locations corresponding to two locations that are half a pixel spacing to the left and half a pixel spacing to the right of the midline.
  • the distance 22 represents the gap between non adjacent mapped filter footprints if the mapping would only be based on the ID filter footprint on the midline.
  • Fig. 5 shows a representation of an improved texel filter footprint.
  • the concept of "stretched texels" is implemented and constitutes an improved approximation of the mapped sheared 2D footprint of the texel using ID filtering.
  • the ID footprint of the texels over the midline ML are stretched according to the local shear factor.
  • four ID footprints on the midline A, B, C, D of four texels are shown in Fig. 5.
  • the ID footprints are stretched resulting in four stretched texels 30.
  • the stretched texels have the same length as the local shear factor.
  • an averaging of the overlapping stretched texels may be performed to deliver the desired anti-aliased and blurred texels 31 that are forwarded to the screen space resampler.
  • the averages 31 of the overlapping parts and hence the blurred texels 31 result in (A+B+C)/3, (B+C+D)/3, and (A+B+C+D)/4.
  • the averaging of n stretched texels requires a delay unit which is able to contain n stretched texels.
  • a maximum of n may be 8, so that, a maximum of 8 delay elements is used.
  • the stretched texels may be limited to a width of 8 texel spacings.
  • alternative widths of the stretched texels are also possible.
  • Fig. 6 depicts that the footprints of Fig. 5 are shrunk.
  • a box low pass reconstruction filter for the stretched texels i.e.
  • the footprint of the box stretched texel is not fitted to the 2D borders 41 of the footprint directly but the footprint 40 is shrunk half a mapped texel spacing on both sides, i.e. the resulting ID footprint extends between the sheared midpoints MP of the footprint. Accordingly, areas a are excluded for contribution, but these are equal to areas b which are included for contribution.
  • the ID footprint 42 over the midline ML is stretched to the ID footprint 41 according to the local shear factor and the final ID footprint 40 is shrunk to extend between the midpoints of the 2D footprint.
  • Fig. 7 shows an illustration of an alternative filter for the 2D footprint.
  • the stretched texel 50 is weighted with a linear weighting at its ends.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Graphics (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Image Generation (AREA)

Abstract

L'invention concerne un processeur graphique équipé d'un système de rendu et de mappage préalable. Le système de rendu comprend un traceur par ligne d'espace texture (TS) permettant de tracer une primitive dans l'espace texture, une unité de production de couleur (PS) permettant de déterminer la couleur de la sortie du traceur par ligne espace-texture (TS) et de transmettre un échantillon de couleur avec des coordonnées, un rééchantillonneur espace écran à deux passages (SSR1, SSR2) permettant de rééchantillonner l'échantillon de couleur déterminé par l'unité de production de couleur (PS), et au moins une unité de filtrage de flou unidimensionnel (1PB, 2PB) associée à au moins un passage dudit rééchantillonneur espace écran (SSR1, SSR2), permettant de réaliser un filtrage unidimensionnel avant le premier passage, au moins.
EP04806602A 2003-12-23 2004-12-21 Processeur infographique et procede de rendu d'images Withdrawn EP1700271A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04806602A EP1700271A1 (fr) 2003-12-23 2004-12-21 Processeur infographique et procede de rendu d'images

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP03104947 2003-12-23
PCT/IB2004/052872 WO2005064541A1 (fr) 2003-12-23 2004-12-21 Processeur graphique et methode de rendu d'images
EP04806602A EP1700271A1 (fr) 2003-12-23 2004-12-21 Processeur infographique et procede de rendu d'images

Publications (1)

Publication Number Publication Date
EP1700271A1 true EP1700271A1 (fr) 2006-09-13

Family

ID=34717248

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04806602A Withdrawn EP1700271A1 (fr) 2003-12-23 2004-12-21 Processeur infographique et procede de rendu d'images

Country Status (5)

Country Link
US (1) US8411099B2 (fr)
EP (1) EP1700271A1 (fr)
JP (1) JP2007517304A (fr)
CN (1) CN100568288C (fr)
WO (1) WO2005064541A1 (fr)

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US7460133B2 (en) * 2006-04-04 2008-12-02 Sharp Laboratories Of America, Inc. Optimal hiding for defective subpixels
CN116263981B (zh) * 2022-04-20 2023-11-17 象帝先计算技术(重庆)有限公司 图形处理器、系统、装置、设备及方法

Citations (1)

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Publication number Priority date Publication date Assignee Title
EP1489560A1 (fr) * 2003-06-17 2004-12-22 Koninklijke Philips Electronics N.V. Préfiltrage primitif des bords

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JPS59127789A (ja) 1983-01-11 1984-07-23 Toyobo Co Ltd インクリボン
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Also Published As

Publication number Publication date
JP2007517304A (ja) 2007-06-28
US8411099B2 (en) 2013-04-02
CN100568288C (zh) 2009-12-09
US20070146381A1 (en) 2007-06-28
CN1898701A (zh) 2007-01-17
WO2005064541A1 (fr) 2005-07-14

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